AreaRenderer sends wrong size Rectangle to fill.beginFill(..)

Steps to reproduce: Create an area chart with a single series
Set the areaFIll of the series to a linearGradient with entries of colors 0xFF0000 and 0x0000FF

Actual Results:
The gradient stops at the lowest mapped data value, which isn't necessarily the base of the chart. So in the situation where you have three data values of 4,10,4. You will have a prymaid of gradient colors at the top of rectangular base.

Expected Results:
Full gradient would render from top most part of series to the base. This becomes especially problematic with custom fills.

Workaround (if any):
I have fixed the bug, here is the needed code to replace current lines 149 and 150
if (fill)
fill.begin(g, new Rectangle(xMin, 0, xMax - xMin, _area.renderedBase));